U.S. patent application number 13/041773 was filed with the patent office on 2011-09-29 for oil passage structure for hydraulic clutch of an engine.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. Invention is credited to Yasushi FUJIMOTO, Kinya MIZUNO, Yoshiaki TSUKADA.
Application Number | 20110233024 13/041773 |
Document ID | / |
Family ID | 43977453 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110233024 |
Kind Code |
A1 |
FUJIMOTO; Yasushi ; et
al. |
September 29, 2011 |
OIL PASSAGE STRUCTURE FOR HYDRAULIC CLUTCH OF AN ENGINE
Abstract
A lubricating oil passage 113 includes an upstream oil passage
113a defined coaxially in a rotational shaft 71 for supplying
lubricating oil to lubricated parts and a downstream oil passage
113b connected to the upstream oil passage 113a for supplying
lubricating oil to canceler chambers 97, 107. The downstream oil
passage 113b may be smaller in diameter than the upstream oil
passage 113a and having at least a portion extending parallel to
the axis of the rotational shaft 71. Control oil passages 111, 112
which have axes parallel to the axis of the rotational shaft 71 are
defined in the rotational shaft 71 such that at least a portion of
the control oil passages 111, 112 is disposed in a range wherein
the downstream oil passage 113b is provided in a direction along
the axis of the rotational shaft 71.
Inventors: |
FUJIMOTO; Yasushi;
(Wako-shi, JP) ; MIZUNO; Kinya; (Wako-shi, JP)
; TSUKADA; Yoshiaki; (Wako-shi, JP) |
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
43977453 |
Appl. No.: |
13/041773 |
Filed: |
March 7, 2011 |
Current U.S.
Class: |
192/85.01 |
Current CPC
Class: |
F16D 25/123
20130101 |
Class at
Publication: |
192/85.01 |
International
Class: |
F16D 25/06 20060101
F16D025/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2010 |
JP |
2010-072638 |
Claims
1. A hydraulic clutch for an engine, the hydraulic clutch being
disposed on a rotational shaft having an axis parallel to a
crankshaft and rotatably supported in a crankcase, the hydraulic
clutch comprising: a clutch piston configured to selectively switch
between an engaged state and a disengaged state in response to
axial movement thereof, wherein said clutch piston comprises
opposite surfaces facing a control hydraulic pressure chamber and a
canceler chamber, respectively; a control oil passage connected to
said control hydraulic pressure chamber; and a lubrication oil
passage, connected to said canceler chamber, configured to supply
lubricating oil to lubricated parts around said rotational shaft,
wherein said lubricating oil passage comprises an upstream oil
passage defined coaxially in said rotational shaft configured to
supply lubricating oil to the lubricated parts around the
rotational shaft, and a downstream oil passage connected to said
upstream oil passage configured to supply lubricating oil from said
upstream oil passage to said canceler chamber, wherein said
downstream oil passage is smaller in diameter than said upstream
oil passage and has at least a portion extending parallel to the
axis of said rotational shaft, and wherein said control oil passage
has an axis parallel to the axis of said rotational shaft and is
defined in said rotational shaft such that at least a portion of
said control oil passage is disposed in a range wherein said
downstream oil passage is provided in a direction along the axis of
said rotational shaft.
2. The hydraulic clutch according to claim 1, wherein a plurality
of said control oil passages and said downstream oil passage that
are connected individually to a plurality of said control hydraulic
pressure chambers which are juxtaposed along the axis of said
rotational shaft are defined in said rotational shaft such that
said control oil passages and said downstream oil passage are
disposed at a position wherein said control oil passages and said
downstream oil passage are partly superposed on said upstream oil
passage on a projection onto a plane perpendicular to the axis of
said rotational shaft.
3. The hydraulic clutch according to claim 2, wherein said control
oil passages and said downstream oil passage are disposed at equal
intervals in a circumferential direction of said rotational
shaft.
4. The hydraulic clutch according to claim 2, wherein said
downstream oil passage and said control oil passages have same
diameters.
5. The hydraulic clutch according to claim 2, wherein said
downstream oil passage and said control oil passages have
respective outer ends along a radial direction of said rotational
shaft which are disposed outwardly of an inner circumferential
surface of said upstream oil passage, and respective inner ends
along the radial direction of said rotational shaft which are
disposed outwardly of a central axis of said upstream oil
passage.
6. The hydraulic clutch according to claim 1, wherein said
downstream oil passage which is drilled together with said control
oil passages axially into one end of said rotational shaft is
connected to said upstream oil passage which is drilled axially
into the other end of said rotational shaft.
7. The hydraulic clutch for an engine according to claim 1, wherein
said hydraulic clutch comprises a first hydraulic clutch and a
second hydraulic clutch mounted on said rotational shaft such that
said first hydraulic clutch is disposed closer to one end of said
rotational shaft along the axis thereof, and said upstream oil
passage of said lubricating oil passage extends from the other
axial end of said rotational shaft such that said upstream oil
passage has an inner end disposed at a position which is aligned,
as viewed in side elevation, with said second hydraulic clutch.
8. The hydraulic clutch according to claim 7, wherein at least a
portion of said downstream oil passage is defined in a cylindrical
tubular shaft which coaxially surrounds said rotational shaft for
applying rotational power to the first and second hydraulic
clutches and extends parallel to the axis of said rotational
shaft.
9. A hydraulic clutch for an engine, the hydraulic clutch being
disposed on a rotational shaft having an axis parallel to a
crankshaft and rotatably supported in a crankcase, the hydraulic
clutch comprising: switching means for selectively switching
between an engaged state and a disengaged state in response to
axial movement of the switching means, wherein said switching means
comprises opposite surfaces facing a control hydraulic pressure
chamber and a canceler chamber, respectively; first supplying
means, connected to said control hydraulic pressure chamber, for
supplying oil; and second supplying means, connected to said
canceler chamber, for supplying lubricating oil to lubricated parts
around said rotational shaft, wherein said second supplying means
comprises an upstream supplying means defined coaxially in said
rotational shaft for supplying lubricating oil to the lubricated
parts around the rotational shaft, and downstream supplying means
connected to said upstream oil passage for supplying lubricating
oil from said upstream supplying means to said canceler chamber,
wherein said downstream supplying means is smaller in diameter than
said upstream supplying means and has at least a portion extending
parallel to the axis of said rotational shaft, and wherein said
first supplying means has an axis parallel to the axis of said
rotational shaft and is defined in said rotational shaft such that
at least a portion of said first supplying means is disposed in a
range wherein said downstream supplying means is provided in a
direction along the axis of said rotational shaft.
10. The hydraulic clutch according to claim 9, further comprising
connecting means for individually connecting said first supplying
means and said downstream supplying means to a plurality of said
control hydraulic pressure chambers which are juxtaposed along the
axis of said rotational shaft, and defining means for defining said
first supplying means and said downstream supplying means in said
rotational shaft such that said first supplying means and said
downstream supplying means are disposed at a position wherein said
first supplying means and said downstream supplying means are
partly superposed on said upstream supplying means on a projection
onto a plane perpendicular to the axis of said rotational
shaft.
11. The hydraulic clutch according to claim 10, wherein said first
supplying means and said downstream supplying means are disposed at
equal intervals in a circumferential direction of said rotational
shaft.
12. The hydraulic clutch according to claim 10, wherein said
downstream supplying means and said first supplying means have the
same diameters.
13. The hydraulic clutch according to claim 10, wherein said
downstream supplying means and said first supplying means have
respective outer ends along a radial direction of said rotational
shaft which are disposed outwardly of an inner circumferential
surface of said upstream supplying means, and respective inner ends
along the radial direction of said rotational shaft which are
disposed outwardly of a central axis of said upstream supplying
means.
14. The hydraulic clutch according to claim 9, wherein said
downstream supplying means which is drilled together with said
first supplying means axially into one end of said rotational shaft
is connected to said upstream supplying means which is drilled
axially into the other end of said rotational shaft.
15. The hydraulic clutch according to claim 9, wherein said
hydraulic clutch comprises a first hydraulic clutch and a second
hydraulic clutch, and further comprising defining means for
defining at least a portion of said downstream supplying means in a
cylindrical tubular shaft which coaxially surrounds said rotational
shaft for applying rotational power to the first and second
hydraulic clutches and extending parallel to the axis of said
rotational shaft.
16. A method, comprising: providing a hydraulic clutch for an
engine, the hydraulic clutch being disposed on a rotational shaft
having an axis parallel to a crankshaft and rotatably supported in
a crankcase; selectively switching, by a clutch piston, between an
engaged state and a disengaged state in response to axial movement
of the clutch piston, wherein said clutch piston comprises opposite
surfaces facing a control hydraulic pressure chamber and a canceler
chamber, respectively; supplying oil by a control oil passage
connected to said control hydraulic pressure chamber; and
supplying, by a lubrication oil passage connected to said canceler
chamber, lubricating oil to lubricated parts around said rotational
shaft, wherein the supplying of the lubricating oil comprises
supplying, by an upstream oil passage defined coaxially in said
rotational shaft, lubricating oil to the lubricated parts around
the rotational shaft, and supplying, by a downstream oil passage
connected to said upstream oil passage, lubricating oil from said
upstream oil passage to said canceler chamber, wherein said
downstream oil passage is smaller in diameter than said upstream
oil passage and has at least a portion extending parallel to the
axis of said rotational shaft, and wherein said control oil passage
has an axis parallel to the axis of said rotational shaft and is
defined in said rotational shaft such that at least a portion of
said control oil passage is disposed in a range wherein said
downstream oil passage is provided in a direction along the axis of
said rotational shaft.
17. The method according to claim 16, further comprising
individually connecting said control oil passage and said
downstream oil passage to a plurality of said control hydraulic
pressure chambers which are juxtaposed along the axis of said
rotational shaft, and defining said control oil passage and said
downstream oil passage in said rotational shaft such that said
control oil passage and said downstream oil passage are disposed at
a position wherein said control oil passage and said downstream oil
passage are partly superposed on said upstream oil passage on a
projection onto a plane perpendicular to the axis of said
rotational shaft.
18. The method according to claim 17, further comprising disposing
said control oil passage and said downstream oil passage at equal
intervals in a circumferential direction of said rotational
shaft.
19. The method according to claim 17, further comprising
configuring said downstream oil passage and said control oil
passage to have the same diameters.
20. The method according to claim 16, further comprising connecting
said downstream oil passage, which is drilled together with said
control oil passage axially into one end of said rotational shaft,
to said upstream oil passage, which is drilled axially into the
other end of said rotational shaft.
Description
BACKGROUND
[0001] 1. Field
[0002] Embodiments of the present invention relate to an oil
passage structure for a hydraulic clutch of engines.
[0003] 2. Description of the Related Art
[0004] Japanese Patent Laid-Open No. Hei 7-42761 describes a
hydraulic clutch wherein lubricating oil is introduced into a
canceler chamber in order to cancel hydraulic pressure which is
generated in a control hydraulic chamber under a centrifugal force.
This hydraulic clutch includes a clutch piston having an end facing
the control hydraulic chamber and the other end facing the canceler
chamber.
[0005] As shown in FIGS. 1 and 2 of Japanese Patent Laid-Open No.
Hei 7-42761, the diameters of a lubricating oil passage and a
control oil passage which are defined in a rotational shaft have to
be about the same as each other in order to avoid physical
interference between the lubricating oil passage and the control
oil passage. There is a demand for a lubricating oil passage of
increased diameter for supplying a sufficient amount of lubricating
oil to lubricated parts.
SUMMARY
[0006] Embodiments of the present invention have been made in view
of the above demand. One object of an embodiment of the present
invention is to provide an oil passage structure for a hydraulic
clutch for engines, which is capable of supplying a sufficient
amount of lubricating oil to lubricated parts.
[0007] One embodiment of the present invention includes an oil
passage structure for a hydraulic clutch of an engine. The
hydraulic clutch is mounted on a rotational shaft having an axis
parallel to a crankshaft and rotatably supported in a crankcase.
The engine includes a hydraulic clutch including a clutch piston
for selectively switching between an engaged state and a disengaged
state in response to axial movement thereof. The clutch piston
having opposite surfaces facing a control hydraulic pressure
chamber and a canceler chamber, respectively. A control oil passage
is connected to the control hydraulic pressure chamber, and a
lubrication oil passage is connected to the canceler chamber, for
supplying lubricating oil to lubricated parts around the rotational
shaft. The lubricating oil passage includes an upstream oil passage
defined coaxially in the rotational shaft for supplying lubricating
oil to the lubricated parts around the rotational shaft, and a
downstream oil passage connected to the upstream oil passage for
supplying lubricating oil from the upstream oil passage to the
canceler chamber. The downstream oil passage may be smaller in
diameter than the upstream oil passage and have at least a portion
extending parallel to the axis of the rotational shaft. The control
oil passage may have an axis parallel to the axis of the rotational
shaft and is defined in the rotational shaft such that at least a
portion of the control oil passage is disposed in a range wherein
the downstream oil passage is provided in a direction along the
axis of the rotational shaft.
[0008] According to another embodiment, a plurality of the control
oil passages and the downstream oil passage which are connected
individually to a plurality of the control hydraulic pressure
chambers of a plurality of the hydraulic clutches which are
juxtaposed along the axis of the rotational shaft are defined in
the rotational shaft such that the control oil passages and the
downstream oil passage are disposed at a position wherein the
control oil passages and the downstream oil passage are partly
superposed on the upstream oil passage on a projection onto a plane
perpendicular to the axis of the rotational shaft.
[0009] According to another embodiment, the control oil passages
and the downstream oil passage are disposed at equal intervals in a
circumferential direction of the rotational shaft.
[0010] According to an embodiment, the downstream oil passage and
the control oil passages have the same diameters.
[0011] According to another embodiment, the downstream oil passage
and the control oil passages have respective outer ends along a
radial direction of the rotational shaft which are disposed
outwardly of an inner circumferential surface of the upstream oil
passage. The downstream oil passage and the control oil passages
also have respective inner ends along the radial direction of the
rotational shaft which are disposed outwardly of a central axis of
the upstream oil passage.
[0012] According to an embodiment, the downstream oil passage which
may be drilled together with the control oil passages axially into
one end of the rotational shaft is connected to the upstream oil
passage which may be drilled axially into the other end of the
rotational shaft.
[0013] According to another embodiment, a first hydraulic clutch
and a second hydraulic clutch are mounted on the rotational shaft
such that the first hydraulic clutch is disposed closer to one end
of the rotational shaft along the axis thereof. The upstream oil
passage of the lubricating oil passage extends from the other axial
end of the rotational shaft such that the upstream oil passage has
an inner end disposed at a position which is aligned, as viewed in
side elevation, with the second hydraulic clutch.
[0014] According to an embodiment, at least a portion of the
downstream oil passage is defined in a cylindrical tubular shaft
which coaxially surrounds the rotational shaft for applying
rotational power to the first and second hydraulic clutches and
extends parallel to the axis of the rotational shaft.
[0015] Another embodiment includes a hydraulic clutch for an
engine. The hydraulic clutch is mounted on a rotational shaft
having an axis parallel to a crankshaft and rotatably supported in
a crankcase. The hydraulic clutch includes switching means for
selectively switching between an engaged state and a disengaged
state in response to axial movement of the switching means. The
switching means comprises opposite surfaces facing a control
hydraulic pressure chamber and a canceler chamber, respectively.
The hydraulic clutch also includes first supplying means, connected
to said control hydraulic pressure chamber, for supplying oil, and
second supplying means, connected to said canceler chamber, for
supplying lubricating oil to lubricated parts around said
rotational shaft. The second supplying means comprises an upstream
supplying means defined coaxially in said rotational shaft for
supplying lubricating oil to the lubricated parts around the
rotational shaft, and downstream supplying means connected to said
upstream oil passage for supplying lubricating oil from said
upstream supplying means to said canceler chamber. The downstream
supplying means is smaller in diameter than said upstream supplying
means and has at least a portion extending parallel to the axis of
said rotational shaft, and the first supplying means has an axis
parallel to the axis of said rotational shaft and is defined in
said rotational shaft such that at least a portion of said first
supplying means is disposed in a range wherein said downstream
supplying means is provided in a direction along the axis of said
rotational shaft.
[0016] Another embodiment includes a method including providing a
hydraulic clutch for an engine which is mounted on a rotational
shaft having an axis parallel to a crankshaft and rotatably
supported in a crankcase. The method also includes selectively
switching, by a clutch piston, between an engaged state and a
disengaged state in response to axial movement of the clutch
piston. The clutch piston comprises opposite surfaces facing a
control hydraulic pressure chamber and a canceler chamber,
respectively. The method also includes supplying oil by a control
oil passage connected to said control hydraulic pressure chamber,
and supplying, by a lubrication oil passage connected to said
canceler chamber, lubricating oil to lubricated parts around said
rotational shaft. The supplying of the lubricating oil comprises
supplying, by an upstream oil passage defined coaxially in said
rotational shaft, lubricating oil to the lubricated parts around
the rotational shaft, and supplying, by a downstream oil passage
connected to said upstream oil passage, lubricating oil from said
upstream oil passage to said canceler chamber. The method also
includes configuring the downstream oil passage to be smaller in
diameter than said upstream oil passage and to have at least a
portion extending parallel to the axis of said rotational shaft.
The control oil passage has an axis parallel to the axis of said
rotational shaft and is defined in said rotational shaft such that
at least a portion of said control oil passage is disposed in a
range wherein said downstream oil passage is provided in a
direction along the axis of said rotational shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a side elevational view of a motorcycle according
to one embodiment.
[0018] FIG. 2 is a side elevational view of a power unit as viewed
in the same direction as FIG. 1.
[0019] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 2.
[0020] FIG. 4 is an enlarged view of a portion of FIG. 3, and a
cross-sectional view taken along line 4-4 of FIG. 5.
[0021] FIG. 5 is a cross-sectional view taken along line 5-5 of
FIG. 4.
[0022] FIG. 6 is a cross-sectional view taken along line 6-6 of
FIG. 5.
[0023] FIG. 7 is a view taken in the direction of arrow 7 in FIG.
4.
[0024] FIG. 8 is a cross-sectional view corresponding to FIG. 4,
according to another embodiment.
DETAILED DESCRIPTION
[0025] Embodiments of the present invention will be described below
with reference to the accompanying drawings.
[0026] One embodiment of the present invention will be described
below with reference to FIGS. 1 through 7. As shown in the example
of FIG. 1, a vehicle, such as a motorcycle, has a vehicle body
frame F including a head pipe 12 on which a front fork 11 is
steerably supported. A front wheel WF may be supported on the front
fork 11 by a shaft. A pair of left and right main frames 13 extend
rearwardly and downwardly from the head pipe 12, and a pair of left
and right down frames 14 may extend rearwardly and downwardly from
the head pipe 12 more steeply than the main frames 13. A pair of
left and right lower frames 15 extend rearwardly from the lower
ends of the down frames 14, and a pair of left and right central
frames 16 extend downwardly from the rear ends of the main frames
13 and are joined to the rear end of the lower frames 15. A pair of
left and right seat rails 17 may extend rearwardly and upwardly
from the rear ends of the main frames 13, and a pair of left and
right rear frames 18 interconnect the lower portions of the central
frames 16 and the rear portions of the seat rails 17. The main
frames 13, the down frames 14, the lower frames 15, and the central
frames 16 can be formed from bent metal pipes integrally joined
together.
[0027] According to an embodiment, a power unit P may include a
multicylinder, for instance two-cylinder, engine E and a gear
transmission M (see FIG. 3). The gear transmission M may be partly
housed in a crankcase 19 of the engine E and disposed in a region
that is surrounded by the main frames 13, the down frames 14, the
lower frames 15, and the central frames 16 such that the power unit
P is supported by the vehicle frame F. A rear wheel WR may be is
driven by power generated by the power unit P and is supported by a
shaft on the rear end of a swing arm 20. The swing arm 20 has a
front end vertically swingably supported by a support shaft 22 on
pivot plates that is disposed on lower portions of the central
frames 16. A fuel tank 24 may be mounted on the main frames 13
above the engine E. The front seat rails 17 can support thereon a
front riding seat 25 disposed rearwardly of the fuel tank 24 and a
rear riding seat 26 disposed rearwardly of the front riding seat
25.
[0028] As shown in the example of FIG. 2, the engine E may include
a crankcase 19 in which a crankshaft 28 having an axis extending
transversely of the motorcycle is rotatably supported. The engine E
may also include a cylinder block 29 having a forwardly inclined
cylinder axis C, coupled to a front upper end of the crankcase 19,
a cylinder head 30 coupled to an upper end of the cylinder block
29, and a head cover 31 coupled to an upper end of the cylinder
head 30. An oil pan 32 may be coupled to a lower portion of the
crankcase 19.
[0029] As also shown in the example of FIG. 3, the crankcase 19 can
include an upper case body 33 and a lower case body 34 which are
separably coupled to each other across a parting plane 35. In an
embodiment, the cylinder block 29 is integrally formed with the
upper case body 33.
[0030] The cylinder block 29 may have a plurality of, for example
two, cylinder bores 36 juxtaposed transversely of the motorcycle.
The crankshaft 28, which extends along the direction in which the
cylinder bores 36 are arranged, i.e., transversely of the
motorcycle, is rotatably supported in the crankcase 19. In one
embodiment, the crankcase 19 has first through third support walls
38, 39, 40 having respective bearing holes 37 through which the
crankshaft 28 extends and in which the crankshaft 28 is supported.
The support walls 38, 39, 40 may be arranged successively from one
end (left end in FIG. 3) of the crankshaft 28 toward the other end
(right end in FIG. 3) of the crankshaft 28. Crank chambers 41 which
correspond individually to the cylinder bores 36 are defined
between adjacent ones of the support walls, i.e., between the first
and second support walls 38, 39 and between the second and third
support walls 39, 40, along the axis of the crankshaft 28 in the
crankcase 19. A transmission chamber 42 which is connected commonly
to the crank chambers 41 is defined in a rear portion of the
crankcase 19.
[0031] According to one embodiment, a left case cover which defines
a generator chamber 45 between itself and the crankcase 19 is
coupled to a left side surface of the crankcase 19. The generator
chamber 45 may house therein a generator 47 including a rotor 48
fixed to the end of the crankshaft 28 which projects into the
generator chamber 45 and a stator 49 surrounded by the rotor 48 and
fixed to the left case cover 46.
[0032] As shown in the example of FIG. 2, a starter motor 50 may be
fixedly disposed above the crankcase 19 and laterally covered by an
upper end portion of the left case cover 46. A speed reducer gear
train 51 for transmitting power from the stator motor 50 may
include a driven gear 52 that is connected to the rotor 48 by a
one-way clutch 53.
[0033] In an embodiment, a drive gear 78 is fixed to the crankshaft
28 closely to the first support wall 38 of the crankcase 19 within
the crankcase 19. As shown in the example of FIG. 2, first and
second balancers 79, 80, i.e., primary balancers, are rotatably
supported in the crankcase 19. The first balancer 79 is disposed
rearwardly and obliquely upwardly of the crankshaft 28, and the
second balancer 80 is disposed forwardly and obliquely downwardly
of the crankshaft 28. The first and second balancers 79, 80 have
driven gears 81, 82, respectively, that are held in driven mesh
with the drive gear 78.
[0034] In an embodiment, a right case cover 55 that defines a
clutch chamber 54 between itself and the crankcase 19 is coupled to
a right side surface of the crankcase 19. The transmission chamber
42 may house therein a gear transmission M including a main shaft
58 and a countershaft 59 that have respective axes parallel to the
crankshaft 28 and rotatably supported in the crankcase 19 and a
plurality of gear trains for gear positions, e.g., first through
sixth gear trains G1 through G6, which can selectively be
established, between the main shaft 58 and the countershaft 59. The
clutch chamber 54 may house therein a primary speed reducer 60 for
transmitting power from the crankshaft 28 and first and second
hydraulic clutches 61, 62 interposed between the primary speed
reducer 60 and the main shaft 58.
[0035] According to one embodiment, the countershaft 59 has an end
rotatably supported on a right side wall of the crankcase 19 by a
roller bearing 83 and the other end projecting from a rear left
side surface of the crankcase 19 with a ball bearing 63 and an
annular seal member 64 being interposed between itself an the
crankcase 19.
[0036] As shown in the example of FIG. 1, rotational power output
from the other end of the countershaft 59 is transmitted to the
rear wheel WR by power transmitting means 65. The power
transmitting means 65 includes a drive sprocket 66 fixed to the end
of the countershaft 59, a driven sprocket 67 mounted coaxially on
the rear wheel WR, and an endless chain 68 trained around the drive
sprocket 66 and the driven sprocket 67.
[0037] According to an embodiment, a pulser 69 is fixed to the end
of the crankshaft 28 in the clutch chamber 54. A rotational speed
sensor 70 is disposed in the clutch chamber 54 in confronting
relation to an outer circumferential portion of the pulser 69 and
fixed to the right case cover 55.
[0038] The main shaft 58 may include a first shaft 71 and a second
shaft 72 in which the first shaft 71 is coaxially and relatively
rotatably inserted. The first gear train G1, the third gear train
G3, and the fifth gear train G5 are provided between the first
shaft 71 and the countershaft 59, and the second gear train G2, the
fourth gear train G4, and the sixth gear train G6 are provided
between the second shaft 72 and the counter shaft 59.
[0039] In one embodiment, the first shaft 71 may be smaller in
diameter than the second shaft 72. The first shaft 71, which
rotatably extends through the crankcase 19, has an end portion
rotatably supported in the right case cover 55 by a first clutch
inner member 91 and a ball bearing 75. The other end of the first
shaft 71 is rotatably supported in the upper case body 33 of the
crankcase 19 by a ball bearing 73. The second shaft 72, which is
greater in diameter than the first shaft 71, has an axially
intermediate portion rotatably supported in the crankcase 19 by a
ball bearing 76. The first shaft 71 has an intermediate portion
coaxially and relatively rotatably extending through the second
shaft 72. A plurality of needle bearings 77 are interposed between
the first shaft 71 and the second shaft 72.
[0040] As also shown in the example of FIG. 4, in an embodiment, a
transmission tubular shaft 85 axially adjacent to the second shaft
72 is axially immovably and relatively rotatably mounted on an
intermediate portion of the first shaft 71 closely to an end
thereof. The first hydraulic clutch 61 is mounted on the first
shaft for selectively transmitting and cutting off power between
the transmission tubular shaft 85 and the first shaft 71. The
second hydraulic clutch 62 is mounted on the first shaft 71 for
selectively transmitting and cutting off power between the
transmission tubular shaft 85 and the second shaft 72.
[0041] Power from the crankshaft 28 can be transmitted to the
transmission tubular shaft 85 through the primary speed reducer 60
and a damper spring 86. The primary speed reducer 60 includes a
drive gear 87 rotatable in unison with the crankshaft 28 and a
driven gear 88 disposed coaxially with the first and second shafts
71, 72 and held in mesh with the drive gear 87. The driven gear 88
is connected to the transmission tubular shaft 85 by the damper
spring 86.
[0042] According to one embodiment, the first hydraulic clutch 61
is disposed more closely to one axial end of the first shaft 71
than the primary speed reducer 60. The first hydraulic clutch 61
may include a first clutch outer member 90 in the form of a
concentric double-walled bottomed hollow cylinder having a first
tubular boss 90a coaxially surrounding the transmission tubular
shaft 85 and a first outer tubular member 90b coaxially surrounding
the first tubular boss 90a. The first clutch outer member 90 may be
relatively nonrotatably coupled to the transmission tubular shaft
85. The first hydraulic clutch 61 may also include a first clutch
inner member 91 having a first inner tubular member 91a coaxially
surrounded by the first outer tubular member 90b. The first clutch
inner member 91 being relatively nonrotatably coupled to the first
shaft 71, with the ball bearing 75 being interposed between the
first clutch inner member 91 and the right case cover 55. The first
hydraulic clutch 61 may also include a plurality of first drive
friction plates 92 relatively nonrotatably engaged by the first
outer tubular member 90b of the first clutch outer member 90, a
plurality of first driven friction plates 93 relatively
nonrotatably engaged by the first inner tubular member 91a of the
first clutch inner member 91 and alternating with the first drive
friction plates 92, a first pressure bearing plate 94 fixedly
supported by the first clutch outer member 90 in confronting
relation to the first drive friction plates 92 and the first driven
friction plates 93 alternating with each other, a first clutch
piston 95 sandwiching the first drive friction plates 92 and the
first driven friction plates 93 between itself and the first
pressure bearing plate 94, the first clutch piston 95 and the first
clutch outer member 90 defining a first control hydraulic pressure
chamber 96 therebetween, and a first spring 98 for biasing the
first clutch piston 95 in a direction to reduce the volume of the
first control hydraulic pressure chamber 96.
[0043] According to one embodiment, the first clutch piston 95 has
an inner circumferential surface held in fluid-tight sliding
contact with the outer circumferential surface of the first boss
90a of the first clutch outer member 90 and an outer
circumferential surface held in fluid-tight sliding contact with
the first outer tubular member 90b of the first clutch outer member
90. In response to a hydraulic pressure buildup in the first
control hydraulic chamber 96, the first clutch piston 95 operates
to grip the first drive friction plates 92 and the first driven
friction plates between itself and the first pressure bearing plate
94. This brings the first hydraulic clutch 61 into an engaged state
wherein the first hydraulic clutch 61 transmits rotational power,
which has been transmitted from the crankshaft 28 through the
primary speed reducer 60, the damper spring 86, and the
transmission tubular shaft 85, to the first clutch outer member 90,
to the first shaft 71.
[0044] In an embodiment, a first canceler chamber 97 is defined
between the first clutch piston 95 and a first wall member 99
opposite to the first control hydraulic chamber 96. The first wall
member 99 has an inner circumferential portion supported on the
first boss 90a of the first clutch outer member 90 and an outer
circumferential portion with which the first clutch piston 95 is
held in fluid-tight sliding contact. The first spring 98 is housed
in the first canceler chamber 97 and interposed between the first
clutch piston 95 and the first wall member 99. Lubricating oil is
introduced into the first canceler chamber 97. Even when forces are
generated to press the first clutch piston 95 under centrifugal
forces upon rotation which act on oil in the first control
hydraulic chamber 96 that is depressurized, since centrifugal
forces also act on oil in the first canceler chamber 97, the first
clutch piston 95 is prevented from being undesirably moved to grip
the first drive friction plates 92 and the first driven friction
plates 93 between itself and the first pressure bearing plate
94.
[0045] According to an embodiment, the second hydraulic clutch 62
is disposed more closely to the other end of the first shaft 71
than the first hydraulic clutch 61, with the primary speed reducer
60 being positioned between the first hydraulic clutch 61 and the
second hydraulic clutch 62. The second hydraulic clutch 62 may
include a second clutch outer member 100 in the form of a
concentric double-walled bottomed hollow cylinder having a second
tubular boss 100a coaxially surrounding the transmission tubular
shaft 85 and a second outer tubular member 100b coaxially
surrounding the second tubular boss 100a. The second clutch outer
member 100 is relatively nonrotatably coupled to the transmission
tubular shaft 85. The second hydraulic clutch 62 may also include a
second clutch inner member 101 having a second inner tubular member
101a coaxially surrounded by the second outer tubular member 100b.
The second clutch inner member 101 is relatively nonrotatably
coupled to the second shaft 72. The second hydraulic clutch 62 may
further include a plurality of second drive friction plates 102
relatively nonrotatably engaged by the second outer tubular member
100b of the second clutch outer member 100, a plurality of second
driven friction plates 103 relatively nonrotatably engaged by the
second inner tubular member 101a of the second clutch inner member
101 and alternating with the second drive friction plates 102, a
second pressure bearing plate 104 fixedly supported by the second
clutch outer member 100 in confronting relation to the second drive
friction plates 102 and the second driven friction plates 103
alternating with each other, a second clutch piston 105 sandwiching
the second drive friction plates 102 and the second driven friction
plates 103 between itself and the second pressure bearing plate
104, the second clutch piston 105 and the second clutch outer
member 100 defining a second control hydraulic pressure chamber 106
therebetween, and a second spring 108 for normally biasing the
second clutch inner member 101 in a direction to reduce the volume
of the second control hydraulic pressure chamber 106.
[0046] In an embodiment, the second clutch piston 105 has an inner
circumferential surface held in fluid-tight sliding contact with
the outer circumferential surface of the second boss 100a of the
second clutch outer member 100, and an outer circumferential
surface held in fluid-tight sliding contact with the second outer
tubular member 100b of the second clutch outer member 100. In
response to a hydraulic pressure buildup in the second control
hydraulic chamber 106, the second clutch piston 105 operates to
grip the second drive friction plates 102 and the second driven
friction plates 103 between itself and the second pressure bearing
plate 104. This brings the second hydraulic clutch 62 into an
engaged state wherein the second hydraulic clutch 62 transmits
rotational power, which has been transmitted from the crankshaft 28
through the primary speed reducer 60, the damper spring 86, and the
transmission tubular shaft 85 to the second clutch outer member
100, to the second shaft 72.
[0047] According to one embodiment, a second canceler chamber 107
is defined between the second clutch piston 105 and a second wall
member 109 opposite to the second control hydraulic chamber 106.
The second wall member 109 has an inner circumferential portion
supported on the second boss 100a of the second clutch outer member
100 and an outer circumferential portion with which the second
clutch piston 105 is held in fluid-tight sliding contact. The
second spring 108 may be housed in the second canceler chamber 107
and interposed between the second clutch piston 105 and the second
wall member 109. Lubricating oil is introduced into the second
canceler chamber 107. Even when forces are generated to press the
second clutch piston 105 under centrifugal forces upon rotation
which act on oil in the second control hydraulic chamber 106 that
is depressurized, since centrifugal forces also act on oil in the
second canceler chamber 107, the second clutch piston 105 is
prevented from being undesirably moved to grip the second drive
friction plates 102 and the second driven friction plates 103
between itself and the second pressure bearing plate 104.
[0048] According to an embodiment, when the first hydraulic clutch
61 is in a power transmitting state and is transmitting power from
the crankshaft 28 to the first shaft 71, it is possible to transmit
the power from the first shaft 71 to the countershaft 59 through a
selectively established one of the first, third, and fifth gear
trains G1, G3, G5. When the second hydraulic clutch 62 is in a
power transmitting state and is transmitting power from the
crankshaft 28 to the second shaft 72, it is possible to transmit
the power from the second shaft 72 to the countershaft 59 through a
selectively established one of the second, fourth, and sixth gear
trains G2, G4, G6.
[0049] As also shown in the examples of FIGS. 5 and 6, the first
shaft 71 has a first control oil passage 111 defined therein which
is connected to the first control hydraulic pressure chamber 96 of
the first hydraulic clutch 61, a second control oil passage 112
defined therein which is connected to the second control hydraulic
pressure chamber 106 of the second hydraulic clutch 62, and a
lubricating oil passage 113 defined therein for supplying
lubricating oil to lubricated parts around the first shaft 71. The
lubricating oil passage 113 is connected to the first and second
canceler chambers 97, 107 of the respective first and second
hydraulic clutches 61, 62.
[0050] The lubricating oil passage 113 is supplied with lubricating
oil from the other end of the first shaft 71. The lubricating oil
passage 113 may include an upstream oil passage 113a defined
coaxially in the first shaft 71 for supplying lubricating oil to
lubricated parts around the first shaft 71, and a downstream oil
passage 113b connected to the upstream oil passage 113a for
supplying lubricating oil from the upstream oil passage 113a to the
first and second canceler chambers 97, 107. In an embodiment, the
downstream oil passage 113b may be smaller in diameter than the
upstream oil passage 113a and have at least a portion extending
parallel to the axis of the first shaft 71. According to one
embodiment, the downstream oil passage 113b, which has the same
diameter as the first and second control oil passages 111, 112, is
defined in the first shaft 71 parallel to the axis of the first
shaft 71 and connected to the upstream oil passage 113a.
[0051] The upstream oil passage 113a may be drilled axially into
the other end of the first shaft 71 such that its outer end is
opens at the other end of the first shaft 71. The upstream oil
passage 113a has an inner end disposed at a position which is
aligned, as viewed in side elevation, with the second hydraulic
clutch 62, among the first and second hydraulic clutches 61, 62
that are juxtaposed in a direction along the axis of the first
shaft 71. The downstream oil passage 113b may be drilled axially
into the one end portion of the first shaft 71 such that it is
connected to the inner end of the upstream oil passage 113a. The
downstream oil passage 113b has its outer end closed by a plug
114.
[0052] In one embodiment, the first shaft 71 has a plurality of oil
holes 115 defined therein at axially spaced locations for supplying
lubricating oil to lubricated parts around the first shaft 71,
e.g., a plurality of locations in the gear transmission M and parts
between the first and second shafts 71, 72, in the present
embodiment. The oil holes 115 may have inner ends connected to the
upstream oil passage 113a of the lubricating oil passage 113. The
first shaft 71 may also have a first canceler chamber oil hole 116
defined therein for introducing lubricating oil into the first
canceler chamber 97 of the first hydraulic clutch 61 and a second
canceler chamber oil hole 117 for introducing lubricating oil into
the second canceler chamber 107 of the second hydraulic clutch 62.
The first and second canceler chamber oil holes 116, 117 may have
inner ends connected to the downstream oil passage 113b of the
lubricating oil passage 113. The first canceler chamber oil hole
116 can be held in fluid communication with the first canceler
chamber 97 through a joint hole 118 that is defined in the
transmission tubular shaft 85 and the first boss 90a of the first
clutch outer member 90. The second chamber oil hole 117 can be held
in fluid communication with the second canceler chamber 107 through
a joint hole 119 that is defined in the transmission tubular shaft
85 and the second boss 100a of the second clutch outer member
100.
[0053] In an embodiment, the first and second control oil passages
111, 112 are defined in the first shaft 71 such that at least a
portion of the first and second control oil passages 111, 112 is
disposed in a range wherein the downstream oil passage 113b is
provided in a direction along the axis of the first shaft 71. The
first control oil passage 111 may be drilled axially into the one
end portion of the first shaft 71 and has an outer end closed by a
plug 120 that is press-fitted into the first shaft 71. The second
control oil passage 112 may be drilled axially into the one end
portion of the first shaft 71 and has an open outer end.
[0054] As shown in the example of FIG. 5, the first control oil
passage 111, the second control oil passage 112, and the downstream
oil passage 113b of the lubricating oil passage 113 are defined in
the first shaft 71 such that they are disposed at a position
wherein they are partly superposed on the upstream oil passage 113a
on a projection onto a plane perpendicular to the axis of the first
shaft 71. In an embodiment, the first control oil passage 111, the
second control oil passage 112, and the downstream oil passage 113b
of the lubricating oil passage 113 are disposed at equal intervals
in the circumferential direction of the first shaft 71.
[0055] The downstream oil passage 113b, the first control oil
passage 111, and the second control oil passage 112 have respective
outer ends P1, P2, P3 along radial directions of the first shaft 71
which are disposed outwardly of the inner circumferential surface
of the upstream oil passage 113a. The downstream oil passage 113b,
the first control oil passage 111, and the second control oil
passage 112 have respective inner ends P4, P5, P6 along radial
directions of the first shaft 71 which are disposed outwardly of
the central axis C of the upstream oil passage 113a.
[0056] According to an embodiment, the first shaft 71 has a first
control hydraulic pressure chamber oil hole 121 defined therein for
guiding control oil into the first control hydraulic pressure
chamber 96 of the first hydraulic clutch 61 and having an inner end
connected to the first control oil passage 111. The first shaft 71
may also have a second control hydraulic pressure chamber oil hole
122 defined therein for guiding control oil into the second control
hydraulic pressure chamber 106 of the second hydraulic clutch 62
and having an inner end connected to the second control oil passage
112. The first control hydraulic pressure chamber oil hole 121 can
be held in fluid communication with the first control hydraulic
pressure chamber 96 through a joint hole 123 that is defined in the
transmission tubular shaft 85 and the first boss 90a of the first
clutch outer member 90. The second control hydraulic pressure
chamber oil hole 122 can be held in fluid communication with the
second control hydraulic pressure chamber 106 through a joint hole
124 that is defined in the transmission tubular shaft 85 and the
second boss 100a of the second clutch outer member 100.
[0057] As also shown in the example of FIG. 7, control oil is
introduced from the right case cover 55 into the first and second
control oil passages 111, 112. The right case cover 55 has a first
supply oil passage 125 connected to the first control oil passage
111 and a second supply oil passage 126 connected to the second
control oil passage 112.
[0058] As shown in the example of FIG. 2, an oil pump 127, which
may serve as an oil supply source, is relatively nonrotatably
connected to the second balancer and is mounted on the lower case
body 34 of the crankcase 19. A hydraulic pressure control unit 130,
which includes a unitized assembly of a first hydraulic pressure
control valve 128 interposed between the first supply oil passage
125 and the oil pump 127 and a second hydraulic pressure control
valve 129 interposed between the second supply oil passage 126 and
the oil pump 127, is mounted on a lower portion of the right case
cover 55.
[0059] A first hydraulic pressure sensor 131 for detecting a
hydraulic pressure in the first supply oil passage 125, and a
second hydraulic pressure sensor 132 for detecting a hydraulic
pressure in the second supply oil passage 126 are mounted on the
right case cover 55.
[0060] According to one embodiment, a cavity 135 having a closed
end wall 135a facing the one end portion of the first shaft 71 and
receiving the one end portion of the first shaft 71 therein is
defined in an inner surface of the right case cover 55 such that
the first and second supply oil passages 125, 126 are open at inner
circumferential surfaces of the cavity 135. In an embodiment, to
keep the first shaft 71 in a constant circumferential position in
the cavity 135, a positioning tooth 136 projecting from the one end
of the first shaft engages in a positioning recess 137 defined in a
circumferential position in the cavity 135.
[0061] One of the first and second control oil passages 111, 112
may be referred to as one particular control oil passage (for
example, in the present embodiment, the second control oil passage
112), and the other as another control oil passage. The first shaft
71 has at least one radial joint hole 138 defined in the one end
thereof and extending radially of the first shaft 71. The radial
joint hole 138 may have an inner end connected to the first control
oil passage 111 which serves the other control oil passage. The
radial joint hole 138 is connected to the first supply oil passage
125, which is a corresponding one of the first and second supply
oil passages 125, 126, in the cavity 135.
[0062] According to an embodiment, a cylindrical tubular member 141
is interposed between the outer circumferential surface of the one
end portion of the first shaft 71 and the inner circumferential
surface of the cavity 135. The cylindrical tubular member 141 has
first and second oil passage forming recesses 139, 140 defined in
outer circumferential surfaces thereof independently of each other
and connected individually to the first and second supply oil
passages 125, 126. The cylindrical tubular member 141 is disposed
inwardly of the inner circumferential surfaces of the first and
second clutch pistons 95, 105 of the respective first and second
hydraulic clutches 61, 62 on a projection onto a plane
perpendicular to the axis of the first shaft 71. Specifically, if
imaginary extensions of the outer circumferential surface of the
cylindrical tubular member 141 toward the first and second
hydraulic clutches 61, 62 are indicated by chain lines L in FIGS. 4
and 6, then the chain lines L extend inwardly of the inner
circumferential surfaces of the first and second clutch pistons 95,
105.
[0063] In an embodiment, an oil chamber 142 that is connected to
the second control oil passage 112 is defined between the closed
end wall 135a of the cavity 135, the end of the first shaft 71, and
an end of the cylindrical tubular member 141. The cylindrical
tubular member 141 may have an axial oil hole 143 defined therein
which extends axially thereof and allowing the second oil passage
forming recess 140, which is one of the first and second oil
passage forming recesses 139, 140, to be connected to the oil
chamber 142, and a radial oil hole 144 defined therein which
extends radially thereof and allowing the first oil passage forming
recess 139, which is the other of the first and second oil passage
forming recesses 139, 140, to be connected to the radial joint hole
138. According to an embodiment, the axial oil hole 143 may be
shaped as an oblong hole which is long in the circumferential
direction of the cylindrical tubular member 141.
[0064] A pair of annular seal members 145, 146 may be mounted on
the outer circumferential surface of the cylindrical tubular member
141 and held in elastic contact with the inner circumferential
surface of the cavity 135 for sealing the opposite sides of the
region where the first and second oil passage forming recesses 139,
140 and the first and second supply oil passages 125, 126 are
connected to each other.
[0065] Advantages of the embodiments discussed above will be
described below. The first and second hydraulic clutches 61, 62 are
mounted on the first shaft 71 which serves as part of the main
shaft 58 and which is rotatably supported in the crankcase 19. The
first shaft 71 has the first control oil passage 111 defined
therein for supplying control oil to the first control hydraulic
pressure chamber 96 of the first hydraulic clutch 61, the second
control oil passage 112 defined therein for supplying control oil
to the second control hydraulic pressure chamber 106 of the second
hydraulic clutch 62, and the lubricating oil passage 113 defined
therein for supplying lubricating oil to the first and second
canceler chambers 97, 107 of the respective first and second
hydraulic clutches 61, 62 and lubricated parts around the first
shaft 71. The lubricating oil passage 113 includes the upstream oil
passage 113a defined coaxially in the first shaft 71 for supplying
lubricating oil to lubricated parts around the first shaft 71, and
the downstream oil passage 113b connected to the upstream oil
passage 113a for supplying lubricating oil from the upstream oil
passage 113a to the first and second canceler chambers 97, 107, the
downstream oil passage 113b being smaller in diameter than the
upstream oil passage 113a. Therefore, a portion of the lubricating
oil passage 113 which supplies lubricating oil to the lubricated
parts can be increased in diameter for supplying a sufficient
amount of lubricating oil to the lubricated parts.
[0066] In one embodiment, the downstream oil passage 113b connected
to the upstream oil passage 113a extends parallel to the axis of
the first shaft 71, and at least a portion of the first and second
control oil passages 111, 112 which have axes parallel to the
downstream oil passage 113b is disposed in a range wherein the
downstream oil passage 113b is provided in the direction along the
axis of the first shaft 71. Therefore, the lubricating oil passage
113 and the first and second control oil passages 111, 112 can be
arranged in a compact layout.
[0067] According to an embodiment, the first and second control oil
passages 111, 112 which are connected individually to the first and
second control hydraulic pressure chambers 96, 106 of the first and
second hydraulic clutches 61, 62 which are juxtaposed along the
axis of the first shaft 71, and the downstream oil passage 113b are
disposed at a position wherein they are partly superposed on the
upstream oil passage 113a on a projection onto a plane
perpendicular to the axis of the first shaft 71. Therefore, the
lubricating oil passage 113 and the first and second control oil
passages 111, 112 can be defined in a compact layout in the first
shaft 71.
[0068] In an embodiment, since the first and second control oil
passages 111, 112 and the downstream oil passage 113b are disposed
at equal intervals in the circumferential direction of the first
shaft 71, the first and second control oil passages 111, 112 and
the downstream oil passage 113b can be disposed in a well-balanced
fashion in the first shaft 71 while maintaining the rigidity of the
first shaft 71 between the first and second control oil passages
111, 112 and the downstream oil passage 113b. As the first control
oil passage 111, the second control oil passage 112, and the
downstream oil passage 113b are of the same diameter, they can
easily be machined in the first shaft 71 for higher
machinability.
[0069] According to one embodiment, the downstream oil passage
113b, the first control oil passage 111, and the second control oil
passage 112 have respective outer ends P1, P2, P3 along radial
directions of the first shaft 71 which are disposed outwardly of
the inner circumferential surface of the upstream oil passage 113a.
The downstream oil passage 113b, the first control oil passage 111,
and the second control oil passage 112 have respective inner ends
P4, P5, P6 along radial directions of the first shaft 71 which are
disposed outwardly of the central axis C of the upstream oil
passage 113a. Therefore, the downstream oil passage 113b, the first
control oil passage 111, and the second control oil passage 112 can
be arranged in a compact layout without mutual physical
interference.
[0070] In an embodiment, the downstream oil passage 113b which is
drilled together with the first and second control oil passages
111, 112 axially into the one end of the first shaft 71 is
connected to the upstream oil passage 113a which is drilled axially
into the other end of the first shaft 71. Consequently, the first
control oil passage 111, the second control oil passage 112, and
the downstream oil passage 113b can be drilled more easily than if
they are drilled into the opposite ends of the first shaft 71.
[0071] In an embodiment, the upstream oil passage 113a of the
lubricating oil passage 113 extends from the axially other end of
the first shaft 71 and has an inner end disposed at a position
which is aligned, as viewed in side elevation, with the second
hydraulic clutch 62, among the first and second hydraulic clutches
61, 62 that are juxtaposed in a direction along the axis of the
first shaft 71, the first hydraulic clutch 61 being disposed
closely to the one end of the first shaft 71 along the axis thereof
and the second hydraulic clutch 62 being disposed more closely to
the other end of the first shaft 71 along the axis thereof than the
first hydraulic clutch 61. Therefore, the upstream oil passage 113a
can be made longer and can supply lubricating oil more smoothly to
the lubricated parts than if the inner end of the upstream oil
passage 113a is positioned more closely to the other end of the
first shaft 71 than the second hydraulic clutch 62.
[0072] According to an embodiment, the first and second control oil
passages 111, 112 are connected individually to the first and
second control hydraulic pressure chambers 96, 106 of the first and
second hydraulic clutches 61, 62. The engine E which incorporates a
twin-clutch mechanism including the first and second hydraulic
clutches 61, 62 can thus be made compact along the axis of the
first shaft 71.
[0073] In an embodiment, the first and second control oil passages
111, 112 are supplied with control oil from the first and second
supply oil passages 125, 126 that are defined in the right case
cover 55 for guiding oil from the oil pump 127. The cavity 135
having the closed end wall 135a facing the one end portion of the
first shaft 71 and receiving the one end portion of the first shaft
71 therein is defined in the inner surface of the right case cover
55 such that the first and second supply oil passages 125, 126 are
open at inner circumferential surfaces of the cavity 135. Of the
first and second control oil passages 111, 112, the second control
oil passage 112 may be referred to as one control oil passage, and
the first control oil passage 111 may be referred to as another
control oil passage. The first shaft 71 has the radial joint hole
138 defined in the one end thereof and extending radially of the
first shaft 71, the radial joint hole 138 having an inner end
connected to the first control oil passage 111 which serves the
other control oil passage. The radial joint hole 138 is connected
to the first supply oil passage 125 in the cavity 135.
[0074] Accordingly, the engine E can be made more compact along the
axis of the first shaft 71 than if a plurality of pipes are
disposed between the first shaft and the right case cover 55 for
providing the first and second control oil passages 111, 112.
[0075] According to one embodiment, the cylindrical tubular member
141 is interposed between the outer circumferential surface of the
one end portion of the first shaft 71 and the inner circumferential
surface of the cavity 135. The cylindrical tubular member 141 has
the first and second oil passage forming recesses 139, 140 defined
in the outer circumferential surfaces thereof independently of each
other and connected individually to the first and second supply oil
passages 125, 126. The oil chamber 142 that is connected to the
second control oil passage 112 is defined between the closed end
wall 135a of the cavity 135, the end of the first shaft 71, and the
end of the cylindrical tubular member 141. The cylindrical tubular
member 141 has the axial oil hole 143 defined therein which extends
axially thereof and allowing the second oil passage forming recess
140, which is one of the first and second oil passage forming
recesses 139, 140, to be connected to the oil chamber 142, and the
radial oil hole 144 defined therein which extends radially thereof
and allowing the first oil passage forming recess 139, which is the
other of the first and second oil passage forming recesses 139,
140, to be connected to the radial joint hole 138. Therefore, the
first and second supply oil passages 125, 126 defined in the right
case cover 55 and the first and second control oil passages 111,
112 defined in the first shaft 71 are connected to each other by a
structure which can be made compact.
[0076] In an embodiment, the cylindrical tubular member 141 is
disposed inwardly of the inner circumferential surfaces of the
first and second clutch pistons 95, 105 of the respective first and
second hydraulic clutches 61, 62 on a projection onto a plane
perpendicular to the axis of the first shaft 71. Consequently, the
right case cover 55 is prevented from being increased in size by
the cylindrical tubular member 141.
[0077] According to one embodiment, the axial oil hole 143 defined
in the cylindrical tubular member 141 is shaped as an oblong hole
which is long in the circumferential direction of the cylindrical
tubular member 141. Compared to an axial oil hole 143 which is
shaped as a circular hole, the cylindrical tubular member 141 is
prevented from being increased in diameter, the axial oil hole 143
is increased in cross-sectional area, and oil flows more smoothly
from the second oil passage forming recess 140 which is one of the
first and second oil passage forming recesses 139, 140 that are
defined in the outer circumferential surface of the cylindrical
tubular member 141 to the oil chamber 142.
[0078] In an embodiment, the pair of annular seal members 145, 146
are mounted on the outer circumferential surface of the cylindrical
tubular member 141 seal the opposite sides of the region where the
first and second oil passage forming recesses 139, 140 and the
first and second supply oil passages 125, 126 are connected to each
other. Therefore, oil flowing from the first and second supply oil
passages 125, 126 through the cylindrical tubular member 141 into
the first and second control oil passages 111, 112 is prevented
from leaking.
[0079] In one embodiment, the plug 120 is press-fitted into the one
end of the first shaft 71 in the cavity 135 to close the axial end
of the first control oil passage 111. Therefore, the first control
oil passage 111 and the oil chamber 142 are simply blocked from
each other.
[0080] Other embodiments of the present invention will be described
below with reference to FIG. 8. Those parts of the embodiments
discussed below which correspond to those of the above-discussed
embodiments are denoted by identical reference characters, and will
not be described in detail below.
[0081] In an embodiment, a first shaft 71 has a first control oil
passage 111 defined therein which is connected to a first control
hydraulic pressure chamber 96 of a first hydraulic clutch 61, and a
second control oil passage 112 defined therein which is connected
to a second control hydraulic pressure chamber 106 of a second
hydraulic clutch 62. A lubricating oil passage 148 for supplying
lubricating oil to lubricated parts around the first shaft 71 is
connected to first and second canceler chambers 97, 107 of the
respective first and second hydraulic clutches 61, 62.
[0082] The lubricating oil passage 148 may include an upstream oil
passage 148a defined coaxially in the first shaft 71 for supplying
lubricating oil to lubricated parts around the first shaft 71, and
a downstream oil passage 148b connected to the upstream oil passage
148a for supplying lubricating oil to the first and second canceler
chambers 97, 107. According to one embodiment, the downstream oil
passage 148b may be smaller in diameter than the upstream oil
passage 148a and have at least a portion extending parallel to the
axis of the first shaft 71. At least a portion of the downstream
oil passage 148b is defined in a cylindrical transmission tubular
shaft 85 which coaxially surrounds the first shaft 71 and extends
parallel to the axis of the first shaft 71.
[0083] In an embodiment, the first and second control oil passages
111, 112 are defined in the first shaft 71 such that at least a
portion of the first and second control oil passages 111, 112 is
disposed in a range wherein the downstream oil passage 148b is
provided in the direction along the axis of the first shaft 71.
[0084] According to this embodiment, since at least a portion of
the downstream oil passage 148b is defined in the cylindrical
transmission tubular shaft 85 which coaxially surrounds the first
shaft 71, the first and second control oil passages 111, 112 that
are defined in the first shaft 71 can be made larger in
diameter.
[0085] According to one embodiment, the lubricating oil passage
includes an upstream oil passage defined coaxially in the
rotational shaft for supplying lubricating oil to the lubricated
parts around the rotational shaft, and a downstream oil passage
connected to the upstream oil passage for supplying lubricating oil
from the upstream oil passage to the canceler chamber. The
downstream oil passage being smaller in diameter than the upstream
oil passage. As a result, at least a portion of the lubricating oil
passage which supplies lubricating oil to the lubricated parts can
be increased in diameter for supplying a sufficient amount of
lubricating oil to the lubricated parts. Furthermore, at least a
portion of the downstream oil passage connected to the upstream oil
passage extends parallel to the axis of the rotational shaft, and
the control oil passage which has an axis parallel to the axis of
the rotational shaft is defined in the rotational shaft such that
at least a portion of the control oil passage is disposed in a
range wherein the downstream oil passage is provided in the
direction along the axis of the rotational shaft. Therefore, the
lubricating oil passage and the control oil passage can be arranged
in a compact layout.
[0086] According to another embodiment, since a plurality of the
control oil passages which are connected individually to a
plurality of the control hydraulic pressure chambers of a plurality
of the hydraulic clutches which are juxtaposed along the axis of
the rotational shaft, and the downstream oil passage are defined in
the rotational shaft such that a plurality of the control oil
passages and the downstream oil passage are disposed at a position
wherein a plurality of the control oil passages and the downstream
oil passage are partly superposed on the upstream oil passage on a
projection onto a plane perpendicular to the axis of the rotational
shaft, the lubricating oil passage and a plurality of the control
oil passages can be defined in a compact layout in the rotational
shaft.
[0087] According to an embodiment, since a plurality of the control
oil passages and the downstream oil passage are disposed at equal
intervals in a circumferential direction of the rotational shaft,
the control oil passages and the downstream oil passage can be
disposed in a well-balanced fashion in the rotational shaft while
maintaining the rigidity of the rotational shaft between the
control oil passages and the downstream oil passage.
[0088] According to another embodiment, since the downstream oil
passage and the control oil passages have the same diameters, they
can easily be machined, thereby enhancing the machinability.
[0089] According to another embodiment, since the downstream oil
passage and the control oil passages have respective outer ends
along a radial direction of the rotational shaft which are disposed
outwardly of an inner circumferential surface of the upstream oil
passage, and respective inner ends along the radial direction of
the rotational shaft which are disposed outwardly of a central axis
of the upstream oil passage, the downstream oil passage and the
control oil passages can be arranged in a compact layout without
mutual physical interference.
[0090] According to another embodiment, since the control oil
passages and the downstream oil passage are drilled axially into
one end of the rotational shaft, and the upstream oil passage is
drilled axially into the other end of the rotational shaft, the
control oil passages and the downstream oil passage can be drilled
more easily than if they are drilled into the opposite ends of the
rotational shaft.
[0091] According to another embodiment, since a first hydraulic
clutch and a second hydraulic clutch are mounted on the rotational
shaft such that the first hydraulic clutch is disposed closer to
one end of the rotational shaft along the axis thereof, and that
the second hydraulic clutch is disposed closer to the other end of
the rotational shaft than the first hydraulic clutch, and the
upstream oil passage of the lubricating oil passage extends from
the other axial end of the rotational shaft such that the upstream
oil passage has an inner end disposed at a position which is
aligned, as viewed in side elevation, with the second hydraulic
clutch, the upstream oil passage can be made longer and can supply
lubricating oil more smoothly to the lubricated parts than if the
inner end of the upstream oil passage is positioned more closely to
the other end of the rotational shaft than the second hydraulic
clutch.
[0092] According to another embodiment, since at least a portion of
the downstream oil passage is defined in a cylindrical tubular
shaft which coaxially surrounds the rotational shaft, the control
oil passage defined in the rotational shaft can be made larger in
diameter.
[0093] While the embodiments of the present invention have been
described above, the present invention is not limited to the above
embodiments, but various changes in design can be made thereto
without departing from the scope of the claims.
DESCRIPTION OF REFERENCE SYMBOLS
[0094] 19 . . . Crankcase [0095] 28 . . . Crankshaft [0096] 61 . .
. First hydraulic clutch [0097] 62 . . . Second hydraulic clutch
[0098] 71 . . . First shaft as rotational shaft [0099] 85 . . .
Transmission tubular shaft as tubular shaft [0100] 95, 105 . . .
Clutch piston [0101] 96, 106 . . . Control hydraulic pressure
chamber [0102] 97, 107 . . . Canceler chamber [0103] 111, 112 . . .
Control oil passage [0104] 113, 148 . . . Lubricating oil passage
[0105] 113a, 148a . . . Upstream oil passage [0106] 113b, 148b . .
. Downstream oil passage [0107] E . . . Engine
* * * * *